Methods of preparing a catalyst

ABSTRACT

A method of preparing a catalyst comprising a) contacting a non-aqueous solvent, a carboxylic acid, and a chromium-containing compound to form an acidic mixture; b) contacting a titanium-containing compound with the acidic mixture to form a titanium treatment solution; c) contacting a pre-formed silica-support comprising from about 0.1 wt. % to about 20 wt. % water with the titanium treatment solution to form a pre-catalyst; and d) thermally treating the pre-catalyst to form the catalyst. A method of preparing a catalyst comprising a) contacting a non-aqueous solvent and a carboxylic acid to form an acidic mixture; b) contacting a titanium-containing compound with the acidic mixture to form a titanium treatment solution; c) contacting a pre-formed chrominated silica-support comprising from about 0.1 wt. % to about 20 wt. % water with the titanium treatment solution to form a pre-catalyst; and d) thermally treating the pre-catalyst to form the catalyst.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of and claims priority to U.S. patentapplication Ser. No. 15/816,145 filed Nov. 17, 2017, published as U.S.Patent Application Publication No. 2019/0153133 A1 and entitled “Methodsof Preparing a Catalyst,” which is incorporated herein by reference inits entirety.

TECHNICAL FIELD

The present disclosure relates to catalyst compositions. Morespecifically, the present disclosure relates to methods of preparingolefin polymerization catalyst compositions and polymers prepared fromsame.

BACKGROUND

An economically important class of olefin polymerization catalystsincludes chromium-silica-titania catalysts. The titanium-containingcompounds used in the production of these catalysts are water-sensitivecompounds and small amounts of water present during production of thecatalyst can result in the ineffective deposition of titania onto thecatalyst. An ongoing need exists for improved methods of preparingchromium-silica-titania catalysts.

SUMMARY

Disclosed herein is a method of preparing a catalyst comprising: a)contacting a non-aqueous solvent, a carboxylic acid, and achromium-containing compound to form an acidic mixture wherein avolumetric ratio of non-aqueous solvent to carboxylic acid is from about1:1 to about 100:1; b) forming a titanium treatment solution bycontacting a titanium-containing compound with the acidic mixture ofstep a) to form the titanium treatment solution; c) contacting apre-formed silica-support comprising from about 0.1 wt. % to about 20wt. % water with the titanium treatment solution to form a pre-catalyst;and d) thermally treating the pre-catalyst by heating to a temperatureof from about 400° C. to about 1000° C. for a time period of from about1 minute to about 24 hours to form the catalyst.

Also disclosed herein is a method of preparing a catalyst comprising: a)contacting a non-aqueous solvent and a carboxylic acid to form an acidicmixture wherein a volume ratio of non-aqueous solvent to carboxylic acidis from about 1:1 to about 100:1; b) forming a titanium treatmentsolution by contacting a titanium-containing compound with the acidicmixture of step a); c) contacting a pre-formed chrominatedsilica-support comprising from about 0.1 wt. % to about 20 wt. % waterwith the titanium treatment solution to form a pre-catalyst; and d)thermally treating the pre-catalyst by heating to a temperature of fromabout 400° C. to about 1000° C. for a time period of from about 1 minuteto about 24 hours to form the catalyst.

Also disclosed herein is a method of preparing a catalyst comprising: a)contacting a non-aqueous solvent and a carboxylic acid to form an acidicmixture wherein a volume ratio of non-aqueous solvent to carboxylic acidis from about 1:1 to about 100:1; b) forming a titanium treatmentsolution by contacting a titanium-containing compound with the acidicmixture of step a; c) contacting a pre-formed silica-support comprisingfrom about 0.1 wt. % to about 20 wt. % water with the titanium treatmentsolution to form a titanated support; d) contacting the titanatedsupport with a chromium-containing compound to form a pre-catalyst; ande) thermally treating the pre-catalyst to form the catalyst.

Also disclosed herein is a method of preparing a catalyst comprising: a)contacting a non-aqueous solvent and a carboxylic acid to form an acidicmixture wherein a volume ratio of non-aqueous solvent to carboxylic acidis from about 1:1 to about 100:1; b) forming a titanium treatmentsolution by contacting a titanium-containing compound with the acidicmixture of step a); c) contacting a pre-formed silica-support comprisingfrom about 0.1 wt. % to about 20 wt. % water with a chromium-containingcompound to form a chrominated support; d) contacting the chrominatedsupport with the titanium treatment solution to form a pre-catalyst; ande) thermally treating the pre-catalyst to form the catalyst.

Also disclosed herein is a method of preparing a catalyst comprising: a)contacting an alcohol solvent and acetic acid form an acidic mixturewherein a volume ratio of the alcohol solvent to acetic acid is fromabout 2:1 to about 25:1; b) forming a titanium treatment solution bycontacting titanium tetraisopropoxide with the acidic mixture of stepa); c) contacting a pre-formed chrominated silica-support with thetitanation treatment solution to form a pre-catalyst wherein waterevolution occurs when the pre-formed chrominated silica-support isheated within a range of from about 180° C. to about 200° C. undervacuum conditions for a period of time ranging from about 8 hours toabout 20 hours; and b) thermally treating the pre-catalyst by heating toa temperature of from about 400° C. to about 1000° C. for a time periodof from about 1 minute to about 24 hours to form the catalyst.

DETAILED DESCRIPTION

This disclosure encompasses: (i) compositions of chromium-silica-titaniacatalysts hereinafter referred to as olefin polymerization catalysts;(ii) methods of preparing olefin polymerization catalysts; and (iii)methods of using olefin polymerization catalysts. This disclosurefurther encompasses the preparation of olefin polymerization catalystsby contacting a pre-formed silica-support with a treatment solutioncomprising a carboxylic acid, a non-aqueous solvent and at least onemetal-containing compound.

In an aspect, a method of preparing an olefin polymerization catalyst ofthe present disclosure comprises contacting a treatment solution with apre-formed silica-support under conditions suitable for formation of theolefin polymerization catalyst. In another aspect, a method of preparingan olefin polymerization catalyst of the present disclosure comprisescontacting a treatment solution with a pre-formed chrominatedsilica-support under conditions suitable for the formation of the olefinpolymerization catalyst. Treatment solutions suitable for use in thepresent disclosure comprise i) a carboxylic acid, (ii) a non-aqueoussolvent and (iii) a transition metal-containing compound. In an aspect,the transition metal-containing compound comprises a titanium-containingcompound; or alternatively a titanium-containing compound and achromium-containing compound.

In an aspect, the treatment solution is a titanium treatment solution(TTS) comprising a carboxylic acid, a non-aqueous solvent, and atitanium-containing compound. Alternatively, the treatment solution is atitanium-chromium treatment solution (TCTS) comprising a carboxylicacid, a non-aqueous solvent, a titanium-containing compound and achromium-containing compound.

In an aspect, a carboxylic acid suitable for use in the treatmentsolutions disclosed herein comprises a C₁ to C₁₅ carboxylic acid;alternatively, a C₁ to C₁₀ carboxylic acid; or alternatively, a C₁ to C₅carboxylic acid. In an aspect, the carboxylic acid comprises formicacid, acetic acid, propionic acid, or a combination thereof.

In an aspect, non-aqueous solvents suitable for use in the treatmentsolutions disclosed herein include without limitation alcohols, ketones,aliphatic hydrocarbons, aromatic hydrocarbons, halocarbons, ethers,acetonitrile, esters, or combinations thereof.

In an aspect, the solvent comprises an ester, a ketone, an alcohol, orcombinations thereof. In an aspect, the non-aqueous solvent comprises aC₁ to C₂₀ ester, a C₁ to C₁₀ ester or alternatively a C₁ to C₅ ester. Inanother aspect, the non-aqueous solvent comprises a C₁ to C₂₀ ketone, aC₁ to C₁₀ ketone or alternatively a C₁ to C₅ ketone. In another aspect,the non-aqueous solvent comprises a C₁ to C₂₀ alcohol, a C₁ to C₁₀alcohol or alternatively a C₁ to C₅ alcohol.

Non-limiting examples of esters which can be utilized as a non-aqueoussolvent include ethyl acetate, propyl acetate, butyl acetate, isobutylisobutyrate, methyl lactate, ethyl lactate and combinations thereof.Non-limiting examples of ketones which can be utilized as a non-aqueoussolvent include acetone, ethyl methyl ketone, methyl isobutyl ketone andcombinations thereof. Non-limiting examples of alcohols which can beutilized as a non-aqueous solvent include methanol, ethanol, n-propanol,isopropanol, n-butanol, isobutanol, pentanol, hexanol, heptanol,octanol, benzyl alcohol, phenol, cyclohexanol or combinations thereof.In an aspect, the non-aqueous solvent suitable for use in the presentdisclosure comprises methanol, ethanol, isopropanol, n-propanol,butanol, acetone, methylethylketone, ethyl acetate, heptane orcombinations thereof.

In an aspect, the solvent comprises an aliphatic hydrocarbon, anaromatic hydrocarbon, a halogenated aliphatic hydrocarbon, a halogenatedaromatic hydrocarbon, or combinations thereof.

In an aspect, the non-aqueous solvent comprises a C₃ to C₂₀ aliphatichydrocarbon; alternatively, a C₄ to C₁₅ aliphatic hydrocarbon; oralternatively, a C₅ to C₁₀ aliphatic hydrocarbon. Aliphatic hydrocarbonswhich can be utilized as the non-aqueous solvent can be cyclic oracyclic and/or can be linear or branched, unless otherwise specified.Non-limiting examples of suitable acyclic aliphatic hydrocarbonnon-aqueous solvents that can be utilized singly or in any combinationinclude propane, iso-butane, n-butane, butane (n-butane or a mixture oflinear and branched C₄ acyclic aliphatic hydrocarbons), pentane(n-pentane or a mixture of linear and branched C₅ acyclic aliphatichydrocarbons), hexane (n-hexane or mixture of linear and branched C₆acyclic aliphatic hydrocarbons), heptane (n-heptane or mixture of linearand branched C₇ acyclic aliphatic hydrocarbons), octane (n-octane or amixture of linear and branched C₈ acyclic aliphatic hydrocarbons), andcombinations thereof.

In an aspect, the non-aqueous solvent comprises an aromatic hydrocarbon.Aromatic hydrocarbons which can be useful as a non-aqueous solvent inthe treatment solution include a C₆ to C₂₀ aromatic hydrocarbon oralternatively, a C₆ to C₁₀ aromatic hydrocarbon. Non-limiting examplesof suitable aromatic hydrocarbons that can be utilized singly or in anycombination in the present disclosure include benzene, toluene, xylene(including ortho-xylene, meta-xylene, para-xylene, or mixtures thereof),ethylbenzene, or combinations thereof.

In an aspect, the non-aqueous solvent comprises a halogenated aliphatichydrocarbon. Halogenated aliphatic hydrocarbons which can be useful as anon-aqueous solvent include C₁ to C₁₅ halogenated aliphatichydrocarbons; alternatively, C₁ to C₁₀ halogenated aliphatichydrocarbons; or alternatively, C₁ to C₅ halogenated aliphatichydrocarbons. The halogenated aliphatic hydrocarbons can be cyclic,acyclic, linear or branched unless otherwise specified. Non-limitingexamples of suitable halogenated aliphatic hydrocarbons which can beutilized include methylene chloride, chloroform, carbon tetrachloride,dichloroethane, trichloroethane, and combinations thereof;alternatively, methylene chloride, chloroform, dichloroethane,trichloroethane and combinations thereof.

In an aspect, the non-aqueous solvent comprises a halogenated aromatichydrocarbon. Halogenated aromatic hydrocarbons which can be useful as anon-aqueous solvent include without limitation C₆ to C₂₀ halogenatedaromatic hydrocarbons; or alternatively, C₆ to C₁₀ halogenated aromatichydrocarbons. Non-limiting examples of suitable halogenated aromatichydrocarbons include chlorobenzene, dichlorobenzene, and combinationsthereof.

In an aspect of the present disclosure, the treatment solution comprisesa titanium-containing compound. Any titanium-containing compoundsuitable for the preparation of an olefin polymerization catalyst of thetype described herein may be used. In a further aspect, anytitanium-containing compound capable of providing effective titanationto the olefin polymerization catalyst when utilizing the treatmentsolution as disclosed herein may be used. In a further aspect, thetitanium-containing compound comprises a tetravalent titanium(Ti⁴⁺)-containing compound or a trivalent titanium (Ti³⁺)-containingcompound. The Ti⁴⁺-containing compound may be any compound thatcomprises tetravalent titanium, alternatively the Ti⁴⁺-containingcompound may be any compound that is able to release a Ti⁴⁺ species upondissolving into solution. The Ti³⁺-containing compound may be anycompound that comprises trivalent titanium, alternatively theTi³⁺-containing compound may be any compound that is able to release aTi³⁺ species upon dissolving into solution.

In an aspect, the titanium-containing compound is an organotitaniumcontaining at least one alkoxide group, or alternatively, at least twoalkoxide groups. Alternatively, the titanium-containing compoundcomprises a titanium tetraalkoxide. In an aspect, the titanium alkoxideis titanium ethoxide Ti(OEt)₄, titanium isopropoxide Ti(OiPr)₄, titaniumn-propoxide Ti(nOPr)₄, titanium butoxide Ti(OBu)₄, titanium2-ethylhexoxide, or combinations thereof. In a further aspect, thetitanium-containing compound comprises a titanium (IV) halide, atitanium (III) halide, or a combination thereof. In an aspect, thetitanium halide is titanium chloride TiCl₄, titanium bromide TiBr₄, or acombination thereof. In a still further aspect, the titanium-containingcompound may be characterized by the general formula Ti(OR¹)₂(acac)₂wherein R¹ can be ethyl, isopropyl, n-propyl, butyl, or a combinationthereof and “acac” is acetylacetonate. Alternatively, thetitanium-containing compound may be characterized by the general formulaTi(OR¹)₂(oxal) wherein R¹ can be ethyl, isopropyl, n-propyl, butyl, or acombination thereof and “oxal” is oxalate.

The amount of the titanium-containing compound comprising the treatmentsolution may be any amount capable of providing effective titanation tothe olefin polymerization catalyst prepared as described herein. In anaspect, the amount of titanium-containing compound (e.g., Ti(OiPr)₄),comprising the treatment solution is based upon the weight ofsilica-support used to prepare the olefin polymerization catalyst. In anaspect, the amount of titanium-containing compound may be a quantitysufficient to prepare an olefin polymerization catalyst comprising fromabout 0.01 wt. % to about 10 wt. %; alternatively, from about 0.5 wt. %to about 5 wt. %; alternatively, from about 1 wt. % to about 5 wt. %; oralternatively, from about 2 wt. % to about 4 wt. %. titanium by weightof the olefin polymerization catalyst. Herein, the percentage oftitanium refers to the final weight percent of titanium associated withthe olefin polymerization catalyst by total weight of the olefinpolymerization catalyst after all processing steps (e.g., afteractivation via calcination). In an aspect, the titanium may beintroduced via a treatment solution where the titanium-containingcompound is present in amounts at least equal to the ranges disclosedfor the amount of titanium present in the olefin polymerizationcatalyst.

In some aspects of the present disclosure, the treatment solutioncomprises a chromium-containing compound. Any chromium-containingcompound suitable for the preparation of an olefin polymerizationcatalyst of the type described herein may be used. In a further aspect,any chromium-containing compound capable of providing a sufficientamount of chromium to the olefin polymerization catalyst when utilizingthe treatment solution as disclosed herein may be used.

For example, the chromium-containing compound may be a water-solublecompound or a hydrocarbon-soluble compound. Examples of water-solublechromium compounds suitable for use in the present disclosure includechromium trioxide, chromium acetate, chromium nitrate, or combinationsthereof. Examples of hydrocarbon-soluble chromium compounds suitable foruse in the present disclosure include tertiary butyl chromate, a diarenechromium (0) compound, biscyclopentadienyl chromium (II), chromium (III)acetylacetonate, or combinations thereof. In one aspect of the presentdisclosure, the chromium-containing compound may be a chromium (II)compound, a chromium (III) compound, or combinations thereof. Suitablechromium (III) compounds include, but are not limited to, chromiumcarboxylates, chromium naphthenates, chromium halides, chromium sulfate,chromium nitrate, chromium dionates, or combinations thereof. Specificchromium (III) compounds include, but are not limited to, chromium (III)sulfate, chromium (III) chloride, chromium (III) nitrate, chromicbromide, chromium (III) acetylacetonate, and chromium (III) acetate.Suitable chromium (II) compounds include, but are not limited to,chromous chloride, chromous bromide, chromous iodide, chromium (II)sulfate, chromium (II) acetate, or combinations thereof.

The amount of the chromium-containing compound comprising the treatmentsolution may be any amount capable of providing a sufficient amount ofchromium to the olefin polymerization catalyst prepared as describedherein. In a further aspect, the amount of chromium-containing compound(e.g., Cr(OAc)₃), comprising the treatment solution is based upon theweight of silica-support used to prepare the olefin polymerizationcatalyst. In an aspect, the amount of chromium-containing compound maybe a quantity sufficient to prepare an olefin polymerization catalystcomprising chromium in the range from about 0.01 wt. % to about 10 wt.%; alternatively, from about 0.5 wt. % to about 5 wt. %; alternatively,from about 1 wt. % to about 5 wt. %; or alternatively, from about 2 wt.% to about 4 wt. % by weight of the olefin polymerization catalyst.Herein, the percentage chromium refers to the final weight percentchromium associated with the olefin polymerization catalyst by totalweight of the olefin polymerization catalyst after all processing steps(e.g., after activation via calcination). In an aspect, the chromium maybe introduced via a treatment solution where the chromium-containingcompound is present in amounts at least equal to the ranges disclosedfor the amount of chromium present in the olefin polymerizationcatalyst.

A treatment solution of the present disclosure comprises a carboxylicacid, a non-aqueous solvent and a titanium-containing compound. In anaspect, the treatment solution may be prepared using any suitablemethodology. For example, a titanium treatment solution (TTS) may beprepared by adding the carboxylic acid to the non-aqueous solvent toform an acidic mixture followed by addition of the titanium-containingcompound. In an aspect, the titanium-containing compound is not added tothe non-aqueous solvent prior to addition of the carboxylic acid. In afurther aspect, the treatment solution further comprises achromium-containing compound and is designated a titanium-chromiumtreatment solution (TCTS). The TCTS may also be prepared using anysuitable methodology. For the example, the TCTS may be prepared byadding the carboxylic acid to the non-aqueous solvent to form an acidicmixture. The chromium-containing compound may then be added to theacidic mixture before addition of the titanium-containing compound;alternatively, the chromium-containing compound may be added afteraddition of the titanium-containing compound to provide the TCTS. In anaspect, the titanium-containing compound is not added to the non-aqueoussolvent prior to addition of the carboxylic acid.

It is further contemplated that the benefits of utilizing a TTS or aTCTS to prepare the olefin polymerization catalyst as disclosed hereinmay be realized through the application of any method that contacts thecarboxylic acid with a mixture of catalyst components prior to additionof the titanium-containing compound. In a non-limiting example, thechromium-containing compound may be added to the non-aqueous solvent toform a solution followed by subsequent, step-wise addition of thecarboxylic acid, the preformed silica-support and, finally, thetitanium-containing compound.

In an aspect, the titanium treatment solution (TTS) comprises avolumetric ratio of non-aqueous solvent to carboxylic acid (e.g., AcOH),in a range of from about 1:1 to about 100:1; or alternatively, fromabout 2:1 to about 25:1. In an aspect, the amount of titanium-containingcompound contained within the TTS comprises an equivalent amount oftitanium to provide in the range of from about 1 wt. % to about 5 wt. %of titanium based upon the weight of the chrominated silica-support. Ina non-limiting example wherein 1.0 kg of chrominated silica-support isused to prepare the olefin polymerization catalyst described herein andthe titanium-containing compound is Ti(OiPr)₄), the TTS comprises in therange of from about 60 g to about 300 g of Ti(OiPr)₄). In still anotherparticular aspect, a molar ratio of carboxylic acid to titanium of theTTS prepared as described herein may range from about 1:1 to about200:1; or alternatively, from about 2:1 to about 150:1.

In an aspect, the titanium-chromium treatment solution (TCTS) comprisesa solvent system comprising two or more non-aqueous solvents. The term“solvent system” as used herein refers only to the two or morenon-aqueous solvents and excludes any other component of the TCTS,(e.g., carboxylic acid). In an aspect, the solvent system of the TCTScomprises a first alcohol and a second alcohol wherein the volumetricratio of the first alcohol to the second alcohol is in the range of fromabout 9:1 to about 1:9, or alternatively from about 7:3 to about 3:7.The TCTS further comprises a volumetric ratio of solvent system tocarboxylic acid (e.g., AcOH), in a range of from about 1:1 to about100:1; or alternatively, from about 2:1 to about 25:1. In an aspect, theamount of chromium-containing compound (e.g., Cr(OAc)₃), containedwithin the TCTS comprises an equivalent amount of chromium to provide inthe range of from about 0.5 wt. % to about 2 wt. % chromium based uponthe weight of the silica-support. In a non-limiting example wherein 1.0kg of silica-support is used to prepare the olefin polymerizationcatalyst described herein and the chromium-containing compound isCr(OAc)₃, the TCTS comprises in the range of from about 22 g to about 88g of Cr(OAc)₃. In an aspect, the amount of titanium-containing compoundcontained within the TTS comprises an equivalent amount of titanium toprovide in the range of from about 1 wt. % to about 5 wt. % of titaniumbased upon the weight of the chrominated silica-support. In anon-limiting example wherein 1.0 kg of silica-support is used to preparethe olefin polymerization catalyst described herein and thetitanium-containing compound is Ti(OiPr)₄), the TTS comprises in therange of from about 60 g to about 300 g of Ti(OiPr)₄). In still anotherparticular aspect, a molar ratio of carboxylic acid to titanium of theTCTS prepared as described herein may range from about 1:1 to about200:1; or alternatively, from about 2:1 to about 150:1.

In an aspect, a treatment solution of the type disclosed herein (e.g.,TTS or TCTS) is contacted with a silica-support. The silica-support maycomprise a pre-formed silica-support or alternatively a pre-formedchrominated silica-support. In an aspect, preparation of an olefinpolymerization catalyst of the type disclosed herein excludes drying ofthe pre-formed silica-support or the pre-formed chrominatedsilica-support prior to contact with any other catalyst component (e.g.,titanium-containing compound). Consequently, the pre-formedsilica-support and/or the pre-formed chrominated silica-support suitablefor use in the present disclosure may be a termed a hydratedsilica-support. Without wishing to be limited by theory, a hydratedsilica-support comprises a silica-support wherein water evolution occurswhen the silica-support is heated within a range of from about 180° C.to about 200° C. under vacuum conditions for a period of time rangingfrom about 8 hours to about 20 hours. In a further aspect, thepre-formed silica-support and/or the pre-formed chrominatedsilica-support may contain from about 0.1 wt. % to about 20 wt. % water;or alternatively from about 0.1 wt. % to about 10 wt. % water based uponthe total weight of the pre-formed silica-support and/or the pre-formedchrominated silica-support.

A pre-formed silica-support and/or a pre-formed chrominatedsilica-support suitable for use in the present disclosure may have asurface area and pore volume effective to provide for the production ofan active olefin polymerization catalyst. In an aspect of the presentdisclosure, the pre-formed silica-support and/or the pre-formedchrominated silica-support possesses a surface area in the range of fromabout 100 m²/gram to about 1000 m²/gram, alternatively from about 250m²/gram to about 1000 m²/gram, alternatively from about 250 m²/gram toabout 700 m²/gram, alternatively from about 250 m²/gram to about 600m²/gram, or alternatively greater than about 250 m²/gram. The pre-formedsilica-support and/or the pre-formed chrominated silica-support may befurther characterized by a pore volume of greater than about 0.9cm³/gram, alternatively greater than about 1.0 cm³/gram, oralternatively greater than about 1.5 cm³/gram. In an aspect of thepresent disclosure, the pre-formed silica-support and/or the pre-formedchrominated silica-support is characterized by a pore volume rangingfrom about 1.0 cm³/gram to about 2.5 cm³/gram. The pre-formedsilica-support and/or the pre-formed chrominated silica-support may befurther characterized by an average particle size of from about 10microns to about 500 microns, alternatively about 25 microns to about300 microns, or alternatively about 40 microns to about 150 microns.Generally, the average pore size of the pre-formed silica-support and/orthe pre-formed chrominated silica-support ranges from about 10 Angstromsto about 1000 Angstroms. In one aspect of the present disclosure, theaverage pore size of the pre-formed silica-support and/or the pre-formedchrominated silica-support is in the range of from about 50 Angstroms toabout 500 Angstroms, while in yet another aspect of the presentdisclosure the average pore size ranges from about 75 Angstroms to about350 Angstroms.

The pre-formed silica-support and/or the pre-formed chrominatedsilica-support may contain greater than about 50 wt. % silica;alternatively, greater than about 80 wt. % silica; alternatively,greater than about 95 wt. % silica based upon the weight of thepre-formed silica-support. The pre-formed silica-support and/or thepre-formed chrominated silica-support may be prepared using any suitablemethod. For example, the pre-formed silica-support and/or the pre-formedchrominated silica-support may be prepared synthetically by hydrolyzingtetrachlorosilane (SiCl₄) with water or by contacting sodium silicatewith a mineral acid. The pre-formed silica-support and/or the pre-formedchrominated silica-support may include additional components that do notadversely affect the catalyst, such as zirconia, alumina, thoria,magnesia, fluoride, sulfate, phosphate, or mixtures thereof.Non-limiting examples of pre-formed silica-support suitable for use inthis disclosure includes ES70 which is a pre-formed silica-supportmaterial with a surface area of 300 m²/gram, and a pore volume of 1.6cm³/gram that is commercially available from PQ Corporation, HA30W whichis a pre-formed chrominated silica-support material that is commerciallyavailable from W. R. Grace and Company, and V398400 which is apre-formed silica-support material that is commercially available fromEvonik.

The pre-formed silica-support and/or the pre-formed chrominatedsilica-support may be present in the olefin polymerization catalyst inan amount of from about 50 wt. % to about 99 wt. %; or alternatively,from about 80 wt. % to about 99 wt. %. Herein the percentage ofpre-formed silica-support and/or the pre-formed chrominatedsilica-support refers to the final weight percent of pre-formedsilica-support and/or the pre-formed chrominated silica-supportassociated with the olefin polymerization catalyst by total weight ofthe olefin polymerization catalyst after all processing steps (e.g.,after activation via calcination).

Disclosed herein are methods of preparing an olefin polymerizationcatalyst composition. In an aspect, a method of preparing an olefinpolymerization catalyst composition comprises contacting one or morecatalyst components. Various sequences for contacting of the catalystcomponents are also disclosed herein, e.g., forming a titanium treatmentsolution (TTS) followed by contacting a pre-formed silica-support withthe TTS. It is contemplated that other sequences for the contacting ofthe catalyst components may also produce an olefin polymerizationcatalyst of the type disclosed herein. Consequently, in an aspect of thepresent disclosure, the catalyst components may be contacted in anyorder or fashion deemed suitable to one of ordinary skill in the artwith the aid of the present disclosure to produce a catalyst of the typedisclosed herein.

In an aspect of the present disclosure, a method for preparation of anolefin polymerization catalyst comprises contacting a non-aqueoussolvent, a carboxylic acid, and a chromium-containing compound, each ofthe type disclosed herein, to form an acidic mixture. The components ofthe acidic mixture may be subsequently contacted with atitanium-containing compound (e.g., Ti(OiPr)₄) to form a TCTS. Themethod for preparation of the olefin polymerization catalyst may furthercomprise contacting the TCTS with a pre-formed silica-support to form apre-catalyst (e.g., a chrominated, titanated support). In yet a furtheraspect, preparation of an olefin polymerization catalyst excludes dryingof the pre-formed silica-support prior to contact of the pre-formedsilica-support with any other catalyst component.

In an aspect of the present disclosure, a method for preparation of anolefin polymerization catalyst comprises contacting a non-aqueoussolvent and a carboxylic acid, both of the type disclosed herein, toform an acidic mixture. The acidic mixture may then be contacted with atitanium-containing compound (e.g., Ti(OiPr)₄) to form a titaniumtreatment solution (TTS). The method for preparation of the olefinpolymerization catalyst may further comprise contacting the TTS with apre-formed chrominated silica-support to generate a pre-catalyst (e.g.,a chrominated, titanated support). In yet a further aspect, preparationof the olefin polymerization catalyst excludes drying of the pre-formedchrominated silica-support prior to contact of the pre-formedchrominated silica-support with any other catalyst component.

In an aspect of the present disclosure, a method for preparation of anolefin polymerization catalyst comprises contacting a non-aqueoussolvent and a carboxylic acid, both of the type disclosed herein, toform an acidic mixture. The components of the acidic mixture may then becontacted with a titanium-containing compound (e.g., Ti(OiPr)₄) to forma TTS. The TTS may then be contacted with a pre-formed silica-support toform a titanated support. The method may further comprise contacting thetitanated support with a chromium-containing compound to form apre-catalyst (e.g., a chrominated, titanated support).

A method for preparation of an olefin polymerization catalyst maycomprise contacting a non-aqueous solvent with a pre-formedsilica-support and a chromium-containing compound, each of the typedisclosed herein, to form a first mixture containing a chrominatedsupport. In an aspect, an acidic mixture is prepared by contacting acarboxylic acid and a non-aqueous solvent, both of the type disclosedherein. The acidic mixture may then be contacted with atitanium-containing compound (e.g., Ti(OiPr)₄) to form a TTS. In anaspect, the method further comprises contacting the TTS with the firstmixture containing the chrominated support to form a pre-catalyst (e.g.,a chrominated, titanated support). In yet a further aspect, preparationof an olefin polymerization catalyst of the type disclosed hereinexcludes drying of the pre-formed silica-support prior to contact of thepre-formed silica-support with any other catalyst component.

In an aspect of the present disclosure, the method further comprisesthermally treating the pre-catalyst (e.g., a chrominated, titanatedsupport) to remove the non-aqueous solvent, the carboxylic acid and anyother volatile compounds associated with the pre-catalyst. The method ofpreparing the olefin polymerization catalyst as described herein may beapplied to a pre-catalyst prepared by any of the methods describedherein. For example, the pre-catalyst may be dried at temperaturesranging from about 25° C. to about 300° C., alternatively from about 50°C. to about 200° C., or alternatively from about 80° C. to about 150° C.to form a dried pre-catalyst. In an aspect of the present disclosure,the dried pre-catalyst is then activated via a calcination step byheating in an oxidizing environment to produce the olefin polymerizationcatalyst. For example, the dried pre-catalyst may be calcined in thepresence of air at a temperature in the range of from about 400° C. toabout 1,000° C., alternatively from about 500° C. to about 900° C., oralternatively from about 500° C. to about 850° C. and for a time periodof from about 1 min to about 24 hours, alternatively from about 1 minuteto about 10 hours, alternatively from about 1 hour to about 24 hours,alternatively from about 1 hour to about 12 hours, alternatively fromabout 3 hours to about 12 hours, alternatively from about 20 min toabout 5 hours, or alternatively from about 1 hour to about 3 hours toproduce the olefin polymerization catalyst. The method of preparing theolefin polymerization catalyst as described herein may be applied to apre-catalyst prepared by any of the methods described herein.

Without wishing to be being limited by theory, it will be appreciated byone of ordinary skill in the art that a treatment solution of the typedisclosed herein (e.g., TTS or TCTS), may immobilize adventitious water.Adventitious water present in the TTS or TCTS is water associated withthe components of the olefin polymerization catalyst prior to thecontacting of the components, i.e., water that is associated with thecarboxylic acid, the non-aqueous solvent, the titanium-containingcompound, the chromium-containing compound, the silica-support andcombinations thereof. In an aspect, the TTS or TCTS may immobilizeadventitious water through non-covalent binding interactions betweenmolecules of the carboxylic acid and molecules of water. It will beappreciated by one of ordinary skill in the art that thetitanium-containing compounds used herein are water-sensitive compoundsthat can be rendered ineffective for the deposition of active titaniumonto a pre-formed silica-support in the presence of adventitious water.Without wishing to be limited by theory, utilization of a treatmentsolution of the type disclosed herein (e.g., TTS or TCTS) in thepreparation of an olefin polymerization catalyst may reduce the amountof free water the titanium is exposed to the extent that effectivetitanation of the support material occurs in the presence of otherhydrated catalyst components. In a further aspect, a catalystpreparation methodology utilizing a treatment solution as describedherein may reduce or eliminate the need for drying of hydrated catalystcomponents (e.g., pre-formed silica-support) prior to use in thepreparation of the olefin polymerization catalysts thereby reducing thetime and costs associated with preparation of catalysts of the typedisclosed herein.

The olefin polymerization catalysts of the present disclosure aresuitable for use in any olefin polymerization method, using varioustypes of polymerization reactors. In an aspect of the presentdisclosure, a polymer of the present disclosure is produced by anyolefin polymerization method, using various types of polymerizationreactors. As used herein, “polymerization reactor” includes any reactorcapable of polymerizing olefin monomers to produce homopolymers and/orcopolymers. Homopolymers and/or copolymers produced in the reactor maybe referred to as resin and/or polymers. The various types of reactorsinclude, but are not limited to those that may be referred to as batch,slurry, gas-phase, solution, high pressure, tubular, autoclave, or otherreactor and/or reactors. Gas phase reactors may comprise fluidized bedreactors or staged horizontal reactors. Slurry reactors may comprisevertical and/or horizontal loops. High pressure reactors may compriseautoclave and/or tubular reactors. Reactor types may include batchand/or continuous processes. Continuous processes may use intermittentand/or continuous product discharge or transfer. Processes may alsoinclude partial or full direct recycle of un-reacted monomer, un-reactedcomonomer, catalyst and/or co-catalysts, diluents, and/or othermaterials of the polymerization process.

Polymerization reactor systems of the present disclosure may compriseone type of reactor in a system or multiple reactors of the same ordifferent type, operated in any suitable configuration. Production ofpolymers in multiple reactors may include several stages in at least twoseparate polymerization reactors interconnected by a transfer systemmaking it possible to transfer the polymers resulting from the firstpolymerization reactor into the second reactor. Alternatively,polymerization in multiple reactors may include the transfer, eithermanual or automatic, of polymer from one reactor to subsequent reactoror reactors for additional polymerization. Alternatively, multi-stage ormulti-step polymerization may take place in a single reactor, whereinthe conditions are changed such that a different polymerization reactiontakes place.

The desired polymerization conditions in one of the reactors may be thesame as or different from the operating conditions of any other reactorsinvolved in the overall process of producing the polymer of the presentdisclosure. Multiple reactor systems may include any combinationincluding, but not limited to multiple loop reactors, multiple gas phasereactors, a combination of loop and gas phase reactors, multiple highpressure reactors or a combination of high pressure with loop and/or gasreactors. The multiple reactors may be operated in series or inparallel. In an aspect of the present disclosure, any arrangement and/orany combination of reactors may be employed to produce the polymer ofthe present disclosure.

According to one aspect of the present disclosure, the polymerizationreactor system may comprise at least one loop slurry reactor. Suchreactors are commonplace, and may comprise vertical or horizontal loops.Monomer, diluent, catalyst system, and optionally any comonomer may becontinuously fed to a loop slurry reactor, where polymerization occurs.Generally, continuous processes may comprise the continuous introductionof a monomer, a catalyst, and/or a diluent into a polymerization reactorand the continuous removal from this reactor of a suspension comprisingpolymer particles and the diluent. Reactor effluent may be flashed toremove the liquids that comprise the diluent from the solid polymer,monomer and/or comonomer. Various technologies may be used for thisseparation step including but not limited to, flashing that may includeany combination of heat addition and pressure reduction; separation bycyclonic action in either a cyclone or hydrocyclone; separation bycentrifugation; or other appropriate method of separation.

Slurry polymerization processes (also known as particle-form processes)are disclosed in U.S. Pat. Nos. 3,248,179, 4,501,885, 5,565,175,5,575,979, 6,239,235, 6,262,191 and 6,833,415, for example; each ofwhich are herein incorporated by reference in their entirety.

Suitable diluents used in slurry polymerization include, but are notlimited to, the monomer being polymerized and hydrocarbons that areliquids under reaction conditions. Examples of suitable diluentsinclude, but are not limited to, hydrocarbons such as propane,cyclohexane, isobutane, n-butane, n-pentane, isopentane, neopentane, andn-hexane. Some loop polymerization reactions can occur under bulkconditions where no diluent is used. An example is polymerization ofpropylene monomer as disclosed in U.S. Pat. No. 5,455,314, which isincorporated by reference herein in its entirety.

According to yet another aspect of the present disclosure, thepolymerization reactor may comprise at least one gas phase reactor. Suchsystems may employ a continuous recycle stream containing one or moremonomers continuously cycled through a fluidized bed in the presence ofthe catalyst under polymerization conditions. A recycle stream may bewithdrawn from the fluidized bed and recycled back into the reactor.Simultaneously, polymer product may be withdrawn from the reactor andnew or fresh monomer may be added to replace the polymerized monomer.Such gas phase reactors may comprise a process for multi-step gas-phasepolymerization of olefins, in which olefins are polymerized in thegaseous phase in at least two independent gas-phase polymerization zoneswhile feeding a catalyst-containing polymer formed in a firstpolymerization zone to a second polymerization zone. One type of gasphase reactor is disclosed in U.S. Pat. Nos. 4,588,790, 5,352,749, and5,436,304, each of which is incorporated by reference in its entiretyherein.

According to still another aspect of the present disclosure, a highpressure polymerization reactor may comprise a tubular reactor or anautoclave reactor. Tubular reactors may have several zones where freshmonomer, initiators, or catalysts are added. Monomer may be entrained inan inert gaseous stream and introduced at one zone of the reactor.Initiators, catalysts, and/or catalyst components may be entrained in agaseous stream and introduced at another zone of the reactor. The gasstreams may be intermixed for polymerization. Heat and pressure may beemployed appropriately to obtain optimal polymerization reactionconditions.

According to yet another aspect of the present disclosure, thepolymerization reactor may comprise a solution polymerization reactorwherein the monomer is contacted with the catalyst composition bysuitable stirring or other means. A carrier comprising an organicdiluent or excess monomer may be employed. If desired, the monomer maybe brought in the vapor phase into contact with the catalytic reactionproduct, in the presence or absence of liquid material. Thepolymerization zone is maintained at temperatures and pressures thatwill result in the formation of a solution of the polymer in a reactionmedium. Agitation may be employed to obtain better temperature controland to maintain uniform polymerization mixtures throughout thepolymerization zone. Adequate means are utilized for dissipating theexothermic heat of polymerization.

Polymerization reactors suitable for the present disclosure may furthercomprise any combination of at least one raw material feed system, atleast one feed system for catalyst or catalyst components, and/or atleast one polymer recovery system. Suitable reactor systems for thepresent invention may further comprise systems for feedstockpurification, catalyst storage and preparation, extrusion, reactorcooling, polymer recovery, fractionation, recycle, storage, loadout,laboratory analysis, and process control.

Conditions that are controlled for polymerization efficiency and toprovide polymer properties include, but are not limited to temperature,pressure, type and quantity of catalyst or co-catalyst, and theconcentrations of various reactants. Polymerization temperature canaffect catalyst productivity, polymer molecular weight and molecularweight distribution. Suitable polymerization temperatures may be anytemperature below the de-polymerization temperature, according to theGibbs Free Energy Equation. Typically, this includes from about 60° C.to about 280° C., for example, and/or from about 70° C. to about 110°C., depending upon the type of polymerization reactor and/orpolymerization process.

Suitable pressures will also vary according to the reactor andpolymerization process. The pressure for liquid phase polymerization ina loop reactor is typically less than 1000 psig (6.9 MPa). Pressure forgas phase polymerization is usually at about 200 psig (1.4 MPa)-500 psig(3.45 MPa). High pressure polymerization in tubular or autoclavereactors is generally run at about 20,000 psig (138 MPa); to 75,000 psig(518 MPa). Polymerization reactors can also be operated in asupercritical region occurring at generally higher temperatures andpressures. Operation above the critical point of a pressure/temperaturediagram (supercritical phase) may offer advantages.

The concentration of various reactants can be controlled to producepolymers with certain physical and mechanical properties. The proposedend-use product that will be formed by the polymer and the method offorming that product may be varied to determine the desired finalproduct properties. Mechanical properties include, but are not limitedto tensile strength, flexural modulus, impact resistance, creep, stressrelaxation and hardness tests. Physical properties include, but are notlimited to density, molecular weight, molecular weight distribution,melting temperature, glass transition temperature, temperature melt ofcrystallization, density, stereoregularity, crack growth, short chainbranching, long chain branching and rheological measurements.

The concentrations of monomer, comonomer, hydrogen, co-catalyst,modifiers, and electron donors are generally important in producingspecific polymer properties. Comonomer may be used to control productdensity. Hydrogen may be used to control product molecular weight.Co-catalysts may be used to alkylate, scavenge poisons and/or controlmolecular weight. The concentration of poisons may be minimized, aspoisons may impact the reactions and/or otherwise affect polymer productproperties. Modifiers may be used to control product properties andelectron donors may affect stereoregularity.

Polymers such as polyethylene homopolymers and copolymers of ethylenewith other mono-olefins may be produced in the manner described aboveusing the polymerization catalysts prepared as described herein.Polymers produced as disclosed herein may be formed into articles ofmanufacture or end use articles using techniques known in the art suchas extrusion, blow molding, injection molding, fiber spinning,thermoforming, and casting. For example, a polymer resin may be extrudedinto a sheet, which is then thermoformed into an end use article such asa container, a cup, a tray, a pallet, a toy, or a component of anotherproduct. Examples of other end use articles into which the polymerresins may be formed include pipes, films, and bottles.

An olefin polymerization catalyst of the type described herein may becontacted with an olefin under conditions suitable for the preparationof a polyolefin. In an aspect, the olefin is ethylene and the polyolefinis polyethylene. Polyethylene prepared using olefin polymerizationcatalysts of this disclosure may be characterized by a melt index (MI),ranging from about 0 g/10 min. to about 5 g/10 min.; alternatively, fromabout 0.01 g/10 min. to about 2 g/10 min.; or alternatively, from about0.05 g/10 min. to about 0.5 g/10 min. The MI refers to the amount of apolymer which can be forced through an extrusion rheometer orifice of0.0825 inch diameter when subjected to a force of 2,160 grams in tenminutes at 190° C., as determined in accordance with ASTM D1238-82,condition E.

Further, the polyethylene prepared as described herein may becharacterized by a high load melt index (HLMI), ranging from about 1g/10 min. to about 1000 g/10 min.; alternatively, from about 3 g/10 min.to about 300 g/10 min.; alternatively, from about 8 g/10 min. to about100 g/10 min; or alternatively, from about 12 g/10 min to about 50 g/10min. The HLMI represents the rate of flow of a molten polymer through anorifice of 0.0825 inch diameter when subjected to a force of 21,600grams at 190° C. as determined in accordance with ASTM D1238-82,condition F.

In an aspect of the present disclosure, the polyethylene prepared asdescribed herein may be characterized by a shear response ranging fromabout 30 to about 1000; alternatively, from about 50 to about 250; oralternatively, less than about 250; alternatively less than about 200;or alternatively, less than about 170. The shear response refers to theratio of high load melt index to melt index (HLMI/MI).

EXAMPLES

The following examples are given as particular aspect of the presentdisclosures of the present disclosure and to demonstrate the practiceand advantages thereof. It is understood that the examples are given byway of illustration and are not intended to limit the specification orthe claims to follow in any manner.

In the following experiments, nPrOH, MeOH, acetic acid (HOAc), and thechromium and titanium reagents were used as received and were not driedprior to use. Type A catalysts were prepared from a chrominatedsilica-support (HA30W, W. R. Grace and Company) which was used asreceived and was not dried prior to use. A titanium-containing compound,either Ti(OiPr)₂(acac)₂ (230 mg per g chrominated silica-support) orTi(OiPr)₄ (180 mg per g chrominated silica-support) was dissolved in amixture of nPrOH and HOAc to provide a TTS of the type disclosed herein.The amount of HOAc in the nPrOH/HOAc mixture ranged from 8% to 22% byvolume based on the combined volume of nPrOH and HOAc. A pre-catalystwas prepared by impregnating the HW30A chrominated silica-support toincipient wetness with the TTS. The pre-catalyst was then dried andcalcined in air for three hours at 650° C. prior to use inpolymerization experiments.

Type B catalysts were prepared from a silica-support (V398400, Evonik)which was used as received and was not dried prior to use. A solventsystem was prepared containing a mixture of 30% by volume MeOH in nPrOH.Cr(OAc)₃ (44 mg per g silica-support) was added to the solvent system,followed by addition of HOAc sufficient to give an acidic solventcontaining 22% by volume HOAc based on the combined volume of thesolvent system and HOAc. Ti(OiPr)₄ (180 mg per g silica-support) wasdissolved in the acidic solvent to provide a TCTS of the type disclosedherein. A pre-catalyst was prepared by impregnating the V398400silica-support to incipient wetness with the TCTS. The pre-catalyst wasthen dried and calcined in air for three hours at 650° C. prior to usein polymerization experiments.

Polymerization tests were conducted in a 2.2 liter stainless-steelreactor equipped with a marine stirrer rotating at 500 rpm. The reactorwas surrounded by a steel jacket, through which a mixture of cold waterand steam was passed to precisely control the temperature to within halfa degree centigrade, with the aid of electronic control instruments.

Unless otherwise stated, a small amount (0.01 to 0.10 grams normally) ofthe solid catalyst prepared as described herein was first charged undernitrogen to the dry reactor. Next 1.2 liter of isobutane liquid wascharged and the reactor and heated up to the 105° C. Finally, ethylenewas added to the reactor to maintain a fixed pressure, 550 psig (3.8MPa), during the experiment. The mixture was stirred continuously forthe specified time, usually around one hour, and the activity was notedby recording the flow of ethylene into the reactor to maintain the setpressure.

After the allotted time, the ethylene flow was stopped and the reactorslowly depressurized and opened to recover a granular polymer powder. Inall cases the reactor was clean with no indication of any wall scale,coating or other forms of fouling. The polymer powder was then removedand weighed. Activity was specified as grams of polymer produced pergram of solid catalyst charged per hour.

The results of polymerization runs are shown in Table 1. The table listseach silica-support, titanium-containing compound, and solvent systemused to prepare the TTS or TCTS utilized in each run. The table alsolists values for polymer properties including melt index, I₁₀ meltindex, high load melt index and shear response. Melt index (MI, g/10min) was determined in accordance with ASTM D1238-82, condition E at190° C. with a 2,160 gram weight. I₁₀ (g/10 min) is the polymer flowrate using a 10 kg weight. The high load melt index (HLMI) of a polymerresin represents the rate of flow of a molten resin through an orificeof 0.0825 inch diameter when subjected to a force of 21,600 grams at190° C. The HLMI values were determined in accordance with ASTM D1238-82condition F.

Comparative run CM-1 is a Type A catalyst containing no titanium andcomparative run CM-2 is a Type A catalyst which was titanated withoutusing a TTS of the present disclosure. CM-1 and CM-2 provide baselinelevels for productivity, activity, and melt index values. Comparativeruns CM-3, CM-4 and CM-5 are Type B catalysts containing no titaniumwhich provide baseline levels for productivity, activity, and melt indexvalues. The melt index values MI, I₁₀, and HLMI indicate the extent oftitanation upon the silica-support where higher melt index valuesindicate more effective (i.e., greater), titanation.

TABLE 1 Run Cat Productivity Activity HLMI I₁₀ MI No. Type Ti SourceSolvent % Ti g PE/g cat g PE/g-cat-h (g/10 min) (g/10 min) (g/10 min.)HLMI/MI CM-1 A None None 0.0 2973 2973 5.45 0.87 0 — CM-2 A Ti(OiPr)₄None 3.5 2230 2487 6.8 1.48 0.07 93 IN-1 A Ti(OiPr)₂(acac)₂ 10% 3.5 31402853 24.4 5.36 0.29 85 CH₃CO₂H IN-2 A Ti(OiPr)₂(acac)₂ 16% 4.5 2902 285431.4 6.81 0.35 90 CH₃CO₂H IN-3 A Ti(OiPr)₄ 8% 3.5 3215 3180 28.6 6.310.34 83 CH₃CO₂H IN-4 A Ti(OiPr)₄ 22% 4.5 3178 3467 39.1 8.69 0.49 80CH₃CO₂H CM-3 B None None 0 2617 3414 3.65 0.53 0 — CM-4 B None None 02704 3452 3.86 0.75 0 — CM-5 B None None 0 2356 2049 3.47 0.62 0 — IN-5B Ti(OiPr)₄ 22% 3.0 2664 2906 15.8 3.16 0.13 123  CH₃CO₂H IN-6 BTi(OiPr)₄ 22% 3.0 2924 2658 12.5 2.50 0.08 158  CH₃CO₂H CM-6 C* CogelNone 2.5 3117 2309 19.6 4.22 0.24 82 *Commerically available asMagnapore (W. R. Grace) Cr/Silica/Titania cogel. Pore volume = 2.5 mL/g,surface area of about 500 m²/g.

The data presented in Table 1 indicate that runs carried out withcatalysts prepared as described herein (indicated by the prefix IN)displayed higher melt index values when compared to catalysts notprepared with a treatment solution. For example, runs IN-1 to IN-4display higher melt index values relative to comparative runs using aType A catalyst. Likewise, runs IN-5 to IN-6 display higher melt indexvalues relative to the comparative runs using a Type B catalyst. Theresults indicate that use of a TCTS or a TTS comprising analcohol-acetic acid solvent system as described herein produces highlyeffective titanation on the silica surface of an olefin polymerizationcatalyst. The results also show that use of a TCTS or a TTS as describedherein can produce highly effective titanation on a silica-support thathas not been dried prior to use.

Notably, catalysts prepared as disclosed herein produce polymers havingan increased shear response, even though all catalysts were calcined at650° C. and tested under the same polymerization conditions. The resultsdemonstrate that polymers produced using an olefin polymerizationcatalyst prepared with a TTS as disclosed herein have a lower HLMI/MIratio (i.e., shear response) when compared to polymers produced usingcatalysts prepared in the absence of a TTS.

Additional Disclosure

The following enumerated aspects of the present disclosures are providedas non-limiting examples.

A first aspect which is a method of preparing a catalyst comprising: a)contacting a non-aqueous solvent, a carboxylic acid, and achromium-containing compound to form an acidic mixture wherein avolumetric ratio of non-aqueous solvent to carboxylic acid is from about1:1 to about 100:1; b) forming a titanium treatment solution bycontacting a titanium-containing compound with the acidic mixture ofstep a) to form the titanium treatment solution; c) contacting apre-formed silica-support comprising from about 0.1 wt. % to about 20wt. % water with the titanium treatment solution to form a pre-catalyst;and d) thermally treating the pre-catalyst by heating to a temperatureof from about 400° C. to about 1000° C. for a time period of from about1 minute to about 24 hours to form the catalyst.

A second aspect which is the method of the first aspect wherein thecarboxylic acid comprises a C₁ to C₁₅ carboxylic acid.

A third aspect which is the method of the second aspect wherein a ratioof moles of carboxylic acid to moles of titanium of thetitanium-containing compound is from about 1:1 to about 200:1.

A fourth aspect which is the method of any of the first through thirdaspects wherein water evolution occurs when the pre-formedsilica-support is heated within a range of from about 180° C. to about200° C. under vacuum conditions for a period of time ranging from about8 hours to about 20 hours.

A fifth aspect which is the method of any of the first through fourthaspects wherein the titanium-containing compound comprises a titaniumtetraalkoxide.

A sixth aspect which is the method of any of the first through fifthaspects wherein the non-aqueous solvent is an alcohol solvent, ahydrocarbon solvent, a ketone solvent, an ester solvent or combinationsthereof.

A seventh aspect which is the method of any of the first through sixthaspects wherein the chromium-containing compound comprises chromiumtrioxide, chromium acetate, chromium nitrate, tertiary butyl chromate, adiarene chromium (0) compound, biscyclopentadienyl chromium(II),chromium (III) acetylacetonate, or combinations thereof.

An eighth aspect which is the method of any of the first through seventhaspects wherein the pre-formed silica-support is characterized by asurface area of from about 100 m²/gram to about 1000 m²/gram and a porevolume of from about 1.0 cm³/gram to about 2.5 cm³/gram.

A ninth aspect which is the method of any of the first through eighthaspects wherein an amount of chromium present in catalyst may range fromabout 0.01% to about 10% by weight of the catalyst and an amount oftitanium present in the catalyst may range from about 0.01% to about 10%by weight of the catalyst.

A tenth aspect which is a method of forming a polymer comprisingcontacting the catalyst of any of the first through ninth aspects with amonomer under conditions suitable for formation of a polymer andrecovering the polymer.

An eleventh aspect which is the method of tenth aspect wherein themonomer comprises an ethylene monomer and the polymer comprises anethylene polymer.

A twelfth aspect which is the method of any of the tenth througheleventh aspects wherein the polymer has a high load melt index of fromabout 1 g/10 min to about 1 g/10 min, and a shear response of from about30 to about 1000.

A thirteenth aspect which is the method of any of the tenth throughtwelfth aspects wherein the polymer has a high load melt index that isfrom about 3 to about 6 times greater than the high load melt index of apolymer produced by utilizing an otherwise similar catalyst produced inthe absence of a titanium treatment solution.

A fourteenth aspect which is a method of preparing a catalystcomprising: a) contacting a non-aqueous solvent and a carboxylic acid toform an acidic mixture wherein a volume ratio of non-aqueous solvent tocarboxylic acid is from about 1:1 to about 100:1; b) forming a titaniumtreatment solution by contacting a titanium-containing compound with theacidic mixture of step a); c) contacting a pre-formed chrominatedsilica-support comprising from about 0.1 wt. % to about 20 wt. % waterwith the titanium treatment solution to form a pre-catalyst; and d)thermally treating the pre-catalyst by heating to a temperature of fromabout 400° C. to about 1000° C. for a time period of from about 1 minuteto about 24 hours to form the catalyst.

A fifteenth aspect which is the method of the fourteenth aspect whereinthe carboxylic acid comprises a C₁ to C₁₅ carboxylic acid.

A sixteenth aspect which is the method of any of the fourteenth throughfifteenth aspects wherein a ratio of moles of carboxylic acid to molesof titanium of the titanium-containing compound is from about 1:1 toabout 200:1.

A seventeenth aspect which is the method of any of the fourteenththrough sixteenth aspects wherein water evolution occurs when thepre-formed chrominated silica-support is heated within a range of fromabout 180° C. to about 200° C. under vacuum conditions for a period oftime ranging from about 8 hours to about 20 hours.

An eighteenth aspect which is a method of forming a polymer comprisingcontacting the catalyst of any of the fourteenth through seventeenthaspects with a monomer under conditions suitable for formation of apolymer and recovering the polymer.

An nineteenth aspect which is the method of eighteenth aspect whereinthe monomer comprises an ethylene monomer and the polymer comprises anethylene polymer.

A twentieth aspect which is the method of any of the eighteenth throughnineteenth aspects wherein the polymer has a high load melt index offrom about 1 g/10 min to about 1 g/10 min, and a shear response of fromabout 30 to about 1000.

A twenty-first aspect which is the method of any of the eighteenththrough twentieth aspects wherein the polymer has a high load melt indexthat is from about 3 to about 6 times greater than the high load meltindex of a polymer produced by utilizing an otherwise similar catalystproduced in the absence of a titanium treatment solution.

A twenty-second aspect which is a method of preparing a catalystcomprising: a) contacting a non-aqueous solvent and a carboxylic acid toform an acidic mixture wherein a volume ratio of non-aqueous solvent tocarboxylic acid is from about 1:1 to about 100:1; b) forming a titaniumtreatment solution by contacting a titanium-containing compound with theacidic mixture of step a; c) contacting a pre-formed silica-supportcomprising from about 0.1 wt. % to about 20 wt. % water with thetitanium treatment solution to form a titanated support; d) contactingthe titanated support with a chromium-containing compound to form apre-catalyst; and e) thermally treating the pre-catalyst to form thecatalyst.

An twenty-third aspect which is the method of the twenty-second aspectwherein the carboxylic acid comprises a C₁ to C₁₅ carboxylic acid.

A twenty-fourth aspect which is a method of preparing a catalystcomprising: a) contacting a non-aqueous solvent and a carboxylic acid toform an acidic mixture wherein a volume ratio of non-aqueous solvent tocarboxylic acid is from about 1:1 to about 100:1; b) forming a titaniumtreatment solution by contacting a titanium-containing compound with theacidic mixture of step a); c) contacting a pre-formed silica-supportcomprising from about 0.1 wt. % to about 20 wt. % water with achromium-containing compound to form a chrominated support; d)contacting the chrominated support with the titanium treatment solutionto form a pre-catalyst; and e) thermally treating the pre-catalyst toform the catalyst.

A twenty-fifth aspect which is a method of preparing a catalystcomprising: a) contacting an alcohol solvent and acetic acid form anacidic mixture wherein a volume ratio of the alcohol solvent to aceticacid is from about 2:1 to about 25:1; b) forming a titanium treatmentsolution by contacting titanium tetraisopropoxide with the acidicmixture of step a); c) contacting a pre-formed chrominatedsilica-support with the titanation treatment solution to form apre-catalyst wherein water evolution occurs when the pre-formedchrominated silica-support is heated within a range of from about 180°C. to about 200° C. under vacuum conditions for a period of time rangingfrom about 8 hours to about 20 hours; and b) thermally treating thepre-catalyst by heating to a temperature of from about 400° C. to about1000° C. for a time period of from about 1 minute to about 24 hours toform the catalyst.

While various aspects of the present disclosures have been shown anddescribed, modifications thereof can be made by one skilled in the artwithout departing from the spirit and teachings of the invention. Theaspects of the present disclosures described herein are exemplary only,and are not intended to be limiting. Many variations and modificationsof the invention disclosed herein are possible and are within the scopeof the invention. Where numerical ranges or limitations are expresslystated, such express ranges or limitations should be understood toinclude iterative ranges or limitations of like magnitude falling withinthe expressly stated ranges or limitations (e.g., from about 1 to about10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11, 0.12, 0.13,etc.). Use of the term “optionally” with respect to any element of aclaim is intended to mean that the subject element is required, oralternatively, is not required. Both alternatives are intended to bewithin the scope of the claim. Use of broader terms such as comprises,includes, having, etc. should be understood to provide support fornarrower terms such as consisting of, consisting essentially of,comprised substantially of, etc.

Accordingly, the scope of protection is not limited by the descriptionset out above but is only limited by the claims which follow, that scopeincluding all equivalents of the subject matter of the claims. Each andevery claim is incorporated into the specification as an aspect of thepresent disclosure of the present invention. Thus, the claims are afurther description and are an addition to the aspect of the presentdisclosures of the present disclosure. The discussion of a reference inthe present disclosure is not an admission that it is prior art to thepresent disclosure, especially any reference that may have a publicationdate after the priority date of this application. The presentdisclosures of all patents, patent applications, and publications citedherein are hereby incorporated by reference, to the extent that theyprovide exemplary, procedural or other details supplementary to thoseset forth herein.

What is claimed is:
 1. A method of preparing a catalyst comprising: a)contacting a non-aqueous solvent and a carboxylic acid to form an acidicmixture wherein a volume ratio of non-aqueous solvent to carboxylic acidis from about 1:1 to about 100:1, wherein the non-aqueous solvent is analcohol solvent, a ketone solvent, an ester solvent or combinationsthereof; b) forming a titanium treatment solution by contacting atitanium-containing compound with the acidic mixture of step a); c)contacting a pre-formed chrominated silica-support comprising from about0.1 wt. % to about 20 wt. % water with the titanium treatment solutionto form a pre-catalyst; and d) thermally treating the pre-catalyst byheating to a temperature of from about 400° C. to about 1000° C. for atime period of from about 1 minute to about 24 hours to form thecatalyst.
 2. The method of claim 1 wherein the carboxylic acid comprisesa C₁ to C₁₅ carboxylic acid.
 3. The method of claim 1 wherein thecarboxylic acid comprises a C₁ to C₁₀ carboxylic acid.
 4. The method ofclaim 1 wherein the carboxylic acid comprises a C₁ to C₅ carboxylicacid.
 5. The method of claim 1 wherein the carboxylic acid comprisesformic acid, acetic acid, propionic acid, or a combination thereof. 6.The method of claim 2 wherein a ratio of moles of carboxylic acid tomoles of titanium of the titanium-containing compound is from about 1:1to about 200:1.
 7. The method of claim 1 wherein water evolution occurswhen the pre-formed chrominated silica-support is heated within a rangeof from about 180° C. to about 200° C. under vacuum conditions for aperiod of time ranging from about 8 hours to about 20 hours.
 8. Themethod of claim 1 wherein the titanium-containing compound comprises atitanium tetraalkoxide.
 9. The method of claim 1 wherein thetitanium-containing compound comprises titanium ethoxide Ti(OEt)₄,titanium isopropoxide Ti(OiPr)₄, titanium n-propoxide Ti(nOPr)₄,titanium butoxide Ti(OBu)₄, titanium 2-ethylhexoxide, or combinationsthereof.
 10. The method of claim 1 wherein the carboxylic acid comprisesformic acid, acetic acid, propionic acid, or a combination thereof; andwherein the titanium-containing compound comprises titanium ethoxideTi(OEt)₄, titanium isopropoxide Ti(OiPr)₄, titanium n-propoxideTi(nOPr)₄, titanium butoxide Ti(OBu)₄, titanium 2-ethylhexoxide, orcombinations thereof.
 11. The method of claim 1 wherein thechromium-containing compound comprises chromium trioxide, chromiumacetate, chromium nitrate, tertiary butyl chromate, a diarene chromium(0) compound, biscyclopentadienyl chromium (II), chromium (III)acetylacetonate, or combinations thereof.
 12. The method of claim 1wherein the pre-formed silica-support is characterized by a surface areaof from about 100 m²/gram to about 1000 m²/and a pore volume of fromabout 1.0 cm³/gram to about 2.5 cm³/gram.
 13. The method of claim 1wherein an amount of chromium present in catalyst ranges from about0.01% to about 10% by weight of the catalyst and an amount of titaniumpresent in the catalyst ranges from about 0.01% to about 10% by weightof the catalyst.
 14. A method of forming a polymer comprising contactingthe catalyst of claim 13 with a monomer under conditions suitable forformation of a polymer and recovering the polymer.
 15. The method ofclaim 14 wherein the monomer comprises an ethylene monomer and thepolymer comprises an ethylene polymer.
 16. The method of claim 14wherein the polymer has a high load melt index of from about 1 g/10 minto about 1000 g/10 min, and a shear response of from about 30 to about1000.
 17. The method of claim 14 wherein the polymer has a high loadmelt index that is from about 3 to about 6 times greater than the highload melt index of a polymer produced by utilizing an otherwise similarcatalyst produced in the absence of a titanium treatment solution.
 18. Amethod of preparing a catalyst comprising: a) contacting a non-aqueoussolvent and a carboxylic acid to form an acidic mixture wherein a volumeratio of non-aqueous solvent to carboxylic acid is from about 1:1 toabout 100:1, wherein the non-aqueous solvent is an alcohol solvent, aketone solvent, an ester solvent or combinations thereof; b) forming atitanium treatment solution by contacting a titanium-containing compoundwith the acidic mixture of step a); c) contacting a pre-formedsilica-support comprising from about 0.1 wt. % to about 20 wt. % waterwith a chromium-containing compound to form a chrominated support; d)contacting the chrominated support with the titanium treatment solutionto form a pre-catalyst; and e) thermally treating the pre-catalyst toform the catalyst.
 19. The method of claim 18 wherein the carboxylicacid comprises formic acid, acetic acid, propionic acid, or acombination thereof; and wherein the titanium-containing compoundcomprises titanium ethoxide Ti(OEt)₄, titanium isopropoxide Ti(OiPr)₄,titanium n-propoxide Ti(nOPr)₄, titanium butoxide Ti(OBu)₄, titanium2-ethylhexoxide, or combinations thereof.
 20. The method of claim 19wherein a ratio of moles of carboxylic acid to moles of titanium of thetitanium-containing compound is from about 1:1 to about 200:1.